Which has more human data?

Going by the research status on each profile (Selank: Approved outside US; Semax: Approved outside US), they carry the same label, so the status alone does not separate them. Each profile's References section lists the studies, with the species and study type.

What are the half-lives?

Selank: No published PK data found. Semax: No published PK data found. Figures are as reported in the cited studies, with the species where stated.

Are they FDA-approved?

Selank: research status “Approved outside US”. Not FDA-approved; not among the six peptides PCAC recommended for the 503A Bulks List in July 2026. Semax: research status “Approved outside US”. Not FDA-approved. Removed from 503A Category 2 on April 15, 2026. PCAC recommended for the 503A Bulks List (advisory); awaiting FDA rulemaking; not lawfully compoundable under 503A as of Sept 17, 2026. PCAC vote: 8–5–1 (yes–no–abstain), July 24, 2026. See the FDA peptide regulatory tracker for sourced compounding status.

How are they administered in the research?

Selank: Intranasal. Semax: Intranasal. This describes the published studies and is not a recommendation for human use.

Selank vs Semax: Research Comparison

Built from the Selank, Semax research profiles · Profiles last updated October 1, 2026 · Reviewed by The Peptide Dispatch Editorial Team

TL;DR

This page compares Selank and Semax using only their research-profile data. Selank (research stage: Approved outside US; half-life: Not established in published research). It is a lab-made peptide thought to act on the brain's calming (GABA) system, based mostly on animal studies. Semax (research stage: Approved outside US; half-life: Not established in published research). It is a peptide studied mainly in rats after stroke, where it changed the activity of inflammation- and nerve-related genes. Educational summary, not medical advice.

Where each point comes from: Clinicalhuman trials and FDA labels Lab / animalrodent, cell and ex vivo studies Community-reporteduser experience and commonly used protocols, not from clinical studies

Educational summary. Everything below is taken from each compound's research profile and describes what was reported in the cited studies — not a promise of results, a dose recommendation, or an endorsement for human use. Not medical advice. Full disclaimer.

Side-by-side comparison

	Selank	Semax
Category	Cognitive	Cognitive
Research status	Approved outside US	Approved outside US
Regulatory note (as of Sept 2026)	Not FDA-approved; not among the six peptides PCAC recommended for the 503A Bulks List in July 2026. Regulatory tracker →	Not FDA-approved. Removed from 503A Category 2 on April 15, 2026. PCAC recommended for the 503A Bulks List (advisory); awaiting FDA rulemaking; not lawfully compoundable under 503A as of Sept 17, 2026. PCAC vote: 8–5–1 (yes–no–abstain), July 24, 2026. Regulatory tracker →
Half-life	No published PK data found	No published PK data found
Administration route	Intranasal	Intranasal
Dosing used in published research (not a recommendation)	0.3 mg/kg i.p. (anxiolytic dose) in rats and mice; single injection in healthy human volunteers in an fMRI study (n=52, dose not in abstract)	6000 micrograms/day intranasally for 10 days, repeated after a 20-day interval, in a clinical study of 110 post-ischaemic-stroke patients; rodent neuroprotection work uses the transient middle cerebral artery occlusion model in rats
Community-reported protocol (not from clinical studies)	Community-reported250–500 mcg, intranasal	Community-reported200–600 mcg, intranasal
How it works (as summarized from the cited research)	In plain terms: It is a lab-made peptide thought to act on the brain's calming (GABA) system, based mostly on animal studies. Proposed mechanism, from animal studies and a review: a synthetic tuftsin analogue proposed to act on GABA-related systems (review, Doyno 2021). Anxiolytic-like effects were reported in rats (Kasian 2017); a human fMRI study (n=52 healthy volunteers) examined its effects on resting-state brain connectivity (Panikratova 2020).	In plain terms: It is a peptide studied mainly in rats after stroke, where it changed the activity of inflammation- and nerve-related genes. Proposed mechanism, from rodent studies: in a rat ischaemia-reperfusion stroke model, semax suppressed inflammatory gene expression and increased expression of neurotransmission-related genes (Filippenkov 2020). Claims that semax raises brain BDNF or modulates dopamine and serotonin come from rodent work, not human studies; in humans, a clinical study of 110 post-stroke patients reported higher plasma BDNF (Gusev 2018).
Effects reported in research (study subjects as stated)	Lab / animalIn rats under chronic mild stress: enhanced the anxiety-reducing effect of diazepam (Kasian 2017) Lab / animalAnxiolytic-like effects in rodent models; limited human data	ClinicalIn a clinical study of 110 post-stroke patients, semax raised plasma BDNF and accelerated functional recovery
Potential side effects	Human safety data outside Russia are limited	Human safety data are limited to small, mostly Russian-language studies and are not characterised to Western regulatory standards Reported effects include headache and irritability
Profile description	Synthetic analog of the immunomodulatory peptide tuftsin, with anxiolytic-like effects reported in rodent models and limited human data. Developed alongside Semax in Russia.	Synthetic peptide derived from ACTH, developed in Russia and approved there for stroke and cognitive disorders. In a clinical study of 110 post-stroke patients, semax raised plasma BDNF and accelerated functional recovery.
References cited on the profile	4	2

Key differences in the published research

Research status: the same on every profile (Approved outside US).
Category: the same on every profile (Cognitive).
Reported half-life: the same on every profile (No published PK data found).
Administration route in the literature: the same on every profile (Intranasal).
Evidence cited: Selank’s profile lists 4 references; Semax’s profile lists 2 references.

Regulatory status

Selank: Not FDA-approved; not among the six peptides PCAC recommended for the 503A Bulks List in July 2026. Details →
Semax: On the FDA peptide regulatory tracker: Removed from Category 2; PCAC recommended for the 503A Bulks List; awaiting FDA rulemaking. Details →

For the sourced, dated status of every peptide in FDA's 2026 compounding actions, see the FDA peptide regulatory tracker.

Frequently Asked Questions

Which has more human data?: Going by the research status on each profile (Selank: Approved outside US; Semax: Approved outside US), they carry the same label, so the status alone does not separate them. Each profile's References section lists the studies, with the species and study type.
What are the half-lives?: Selank: No published PK data found. Semax: No published PK data found. Figures are as reported in the cited studies, with the species where stated.
Are they FDA-approved?: Selank: research status “Approved outside US”. Not FDA-approved; not among the six peptides PCAC recommended for the 503A Bulks List in July 2026. Semax: research status “Approved outside US”. Not FDA-approved. Removed from 503A Category 2 on April 15, 2026. PCAC recommended for the 503A Bulks List (advisory); awaiting FDA rulemaking; not lawfully compoundable under 503A as of Sept 17, 2026. PCAC vote: 8–5–1 (yes–no–abstain), July 24, 2026. See the FDA peptide regulatory tracker for sourced compounding status.
How are they administered in the research?: Selank: Intranasal. Semax: Intranasal. This describes the published studies and is not a recommendation for human use.
How do their proposed mechanisms differ?: Selank: In plain terms: It is a lab-made peptide thought to act on the brain's calming (GABA) system, based mostly on animal studies. Proposed mechanism, from animal studies and a review: a synthetic tuftsin analogue proposed to act on GABA-related systems (review, Doyno 2021). Anxiolytic-like effects were reported in rats (Kasian 2017); a human fMRI study (n=52 healthy volunteers) examined its effects on resting-state brain connectivity (Panikratova 2020). Semax: In plain terms: It is a peptide studied mainly in rats after stroke, where it changed the activity of inflammation- and nerve-related genes. Proposed mechanism, from rodent studies: in a rat ischaemia-reperfusion stroke model, semax suppressed inflammatory gene expression and increased expression of neurotransmission-related genes (Filippenkov 2020). Claims that semax raises brain BDNF or modulates dopamine and serotonin come from rodent work, not human studies; in humans, a clinical study of 110 post-stroke patients reported higher plasma BDNF (Gusev 2018). These are mechanisms proposed in the cited research, at the research stage listed for each compound.

References

Selank

Peptide Selank Enhances the Effect of Diazepam in Reducing Anxiety in Unpredictable Chronic Mild Stress Conditions in Rats
Kasian A, Kolomin T, Andreeva L, Bondarenko E, Myasoedov N, Slominsky P et al. Behavioural neurology. 2017. PMID: 28280289.
Study type: Rat chronic stress model.
DOI: 10.1155/2017/5091027 · PubMed
Selank, a Peptide Analog of Tuftsin, Attenuates Aversive Signs of Morphine Withdrawal in Rats
Konstantinopolsky MA, Chernyakova IV, Kolik LG. Bulletin of experimental biology and medicine. 2022. PMID: 36322304.
Study type: Rat, 0.3 mg/kg i.p..
DOI: 10.1007/s10517-022-05624-x · PubMed
Functional Connectomic Approach to Studying Selank and Semax Effects
Panikratova YR, Lebedeva IS, Sokolov OY, Rumshiskaya AD, Kupriyanov DA, Kost NV et al. Doklady biological sciences : proceedings of the Academy of Sciences of the USSR, Biological sciences sections. 2020. PMID: 32342318.
Study type: Human fMRI, n=52 healthy volunteers.
DOI: 10.1134/S001249662001007X · PubMed
Sedative-Hypnotic Agents That Impact Gamma-Aminobutyric Acid Receptors: Focus on Flunitrazepam, Gamma-Hydroxybutyric Acid, Phenibut, and Selank
Doyno CR, White CM. Journal of clinical pharmacology. 2021. PMID: 34396551.
Study type: Review.
DOI: 10.1002/jcph.1922 · PubMed

Semax

[The efficacy of semax in the tretament of patients at different stages of ischemic stroke]
Gusev EI, Martynov MY, Kostenko EV, Petrova LV, Bobyreva SN. Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova. 2018. PMID: 29798983.
Study type: Clinical trial, n=110 post-ischaemic-stroke patients, 6000 mcg/day x 10 days x 2 courses.
DOI: 10.17116/jnevro20181183261-68 · PubMed
Novel Insights into the Protective Properties of ACTH((4-7))PGP (Semax) Peptide at the Transcriptome Level Following Cerebral Ischaemia-Reperfusion in Rats
Filippenkov IB, Stavchansky VV, Denisova AE, Yuzhakov VV, Sevan'kaeva LE, Sudarkina OY et al. Genes. 2020. PMID: 32580520.
Study type: Rat tMCAO model, RNA-Seq.
DOI: 10.3390/genes11060681 · PubMed

Read the full profiles

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Educational content — not medical advice. Effects described are drawn from cited research in study subjects.

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